| 摘要 |
PURPOSE:To enhance flaw detection accuracy by automatically performing the setting of a phase with high accuracy, by calculating a direction in which the dispersion of distribution formed by a measuring point group becomes max. on a vector plane, which has the horizontal and vertical components of phase detection output as coordinates axes as the indicating direction of lift-off variation. CONSTITUTION:A probe 7 is arranged to an object 6 to be inspected in close vicinity to the predetermined position in the surface side thereof and an eddy current is generated in the object 6 to be inspected by an AC current with single frequency made to flow to the probe 7. The flaw detection signal of the probe 7 is sent to an eddy current flaw detector 8 to receive amplification/phase detection, and horizontal and vertical phase detection outputs (x), (y) are outputted as digital signals. A calculator 9 samples the phase detection outputs (x), (y) at a plurality of measuring points at every definite measuring section and calculates the direction in which the dispersion of distribution formed by the measuring point group becomes max. on a vector plane, which has the horizontal and vertical components (x), (y) thereof as coordinates axes, as the indicating direction of lift-off variation and sets the same as new coordinates axes to apply phase correction to the phase detection output at each measuring point by a phase correction apparatus 17.
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